PoC service is a half-duplex communication based on VOIP, and is capable of supporting one-to-one or one-to-many sessions. A session initiator may initiate a session with a group of users via a group ID or a list of called users. During the session, only one user is permitted to speak at one time. A user may acquire a floor by submitting a request and then obtaining a grant from a server.
A PoC system includes at least one PoC server and PoC clients. The PoC clients reside in mobile terminals and are adapted to access the PoC service. The PoC server provides the PoC service with network functions of application layer, and may be classified as a PoC control server or a PoC participation function server by its functions. The PoC control server provides functions such as centralized PoC session manipulation, media distribution, Talk Burst control and so on. The PoC control server does not communicate with the PoC clients directly, and instead, interacts with the PoC clients via the PoC participation function server.
The PoC service provides supports for a user to send personal instant notification messages. In such a way, a sender may express his/her desire to establish a one-to-one PoC session with a particular party. When the party receives the message, the session with the sender sending the personal instant message may be established by simply pressing a key.
There are some PoC service settings in the PoC service, including Instant Personal Alert Barring (IAB), Incoming Session Barring (ISB), etc. The IAB serves to reject personal instant notification messages received from the network side, whereas the ISB serves to reject calls received from the network side. Users present these settings to the participation function server when starting their PoC terminals.
PoC voice mailbox is one of system functions, in the PoC service, for answering a session on behave of a called user in the case that he/she is not accessible (no reply or busy). The access to a PoC voice mailbox is similar to a PoC client. A user may also leave a message in his/her voice mailbox prior to a session, so that other users who then call him/her will receive the message. If someone leaves a message in the user's voice mailbox, the number of existing voice messages will be displayed on the terminal, and then, the user may receive the messages by accessing his/her voice mailbox.
In the case that a voice message exits, the PoC server initiatively initiates a session between the PoC user and his/her voice mailbox, so that the PoC user may receive the message in the voice mailbox.
The prior art has the following deficiencies:
1) Existing voice mailboxes are designed only for one-to-one sessions, and always play a voice prompt when they are connected to. In practical applications, however, a one-to-many session is implemented in many scenarios, in which case many voice mailboxes will be connected to. In the case of one-to-many session, it is time consuming and not a good experience for users (e.g., all the users online will hear the voice prompt) if the voice prompt is present for each accessed mailbox as in a one-to-one session.
2) Because of the manner of direct telephone calls adapted in case of voice message in the prior art, a user cannot be notified at all if he/she has set the ISB on.
3) The user has to receive the voice message via a telephone call in the PoC service, resulting inconvenience for the user and inadequate utilization of the PoC service resources.